Conventionally, in order to inspect the states of connection points and other fault points of optical fibers laid down as optical communication lines, an optical time domain reflectometer (OTDR), more commonly known as an optical pulse tester, has been used.
This OTDR is connected to one end of an optical fiber to be measured, and a measuring pulsed light is incident into the optical fiber from the one end, which makes it possible to measure various losses in the optical fiber, to identify locations of losses, to measure the position of the far end, and the like based on an arrival time and a level of received light of a reflected light (backscattered light) returned from the optical fiber.
As such an OTDR, for example, an optical pulse tester disclosed in Pat. Document 1 is well known.
FIG. 14 is a schematic block diagram showing a general OTDR disclosed in Pat. Document 1.
As shown in FIG. 14, the OTDR disclosed in Pat. Document 1 makes a pulse current at a driving circuit 102 by an electric pulse from a timing generating unit 101, and makes a light source 103 emit light.
An optical pulse emitted from the light source 103 passes thorough an optical directional coupler 104 to be incident into an optical fiber 110.
Then, a return light such as a backscattered light, a reflected light, or the like from the optical fiber 110 is transmitted from the optical directional coupler 104 to an optical receiver 105.
This optical receiver 105 transforms the received light into an electric signal to be transmitted to an amplifier 106.
In this manner, after outputs from the optical receiver 105 are amplified by the amplifier 106, they are transformed into digital signals, and are summed and averaged by an average response processor 107.
The summed and averaged output from the average response processor 107 is logarithmically converted by a logarithmic conversion unit 108, and thereafter, the converted data is displayed on a display unit 109.
Such a structure is a structure of a conventional general OTDR.
In the OTDR shown in FIG. 14, in order to make an attempt to equate signal-to-noise ratios of measured waveforms, a signal-to-noise ratio comparison unit 111 and a data storage unit 112 are further provided.
Namely, the data logarithmically converted at the logarithmic conversion unit 108 is transmitted to the signal-to-noise ratio comparison unit 111 to be compared with a set value set in advance in the signal-to-noise ratio comparison unit 111.
The data whose signal-to-noise ratio has been improved by carrying out summing and averaging or the like at the average response processor 107 again based on the comparison result from the signal-to-noise ratio comparison unit 111 is transmitted to the data storage unit 112.
The data storage unit 112 combines the data whose signal-to-noise ratio has been improved and data which has been stored in advance in the data storage unit 112, and transmits the combined data to the display unit 109.
Incidentally, as a series of operation processes of a current cable laying/maintenance construction of an optical fiber, first, an operator measures an optical fiber serving as a measuring object by using an OTDR, and stores measured data thereof into an external storage medium, for example, a floppy (registered trademark) disk, a memory card, a USB memory, or the like, or an internal memory built into the OTDR, and brings it back from a work site to an office.
Further, the operator makes notes of information such as a core wire number, a core wire name, and the like on the measured optical fiber at the time of recording measured data, and records such so as to associate the measured optical fiber with the measured data.
Then, the operator generates a report by using a report generator application operating on a terminal machine such as, for example, a personal computer while comparing the measured data brought back to the office and the notes, and ends the series of cable laying/maintenance constructions are completed by delivering the report to relevant departments.
However, in accordance with operation processes in such a series of cable laying/maintenance constructions, it is necessary for the operator to generate a report while carrying out association for every optical fiber by comparing measured data of all the optical fibers and note-based information, in the case of a construction in which laying and characteristic evaluations of several hundred multicore optical fibers are carried out per day. This brings about a problem that the report generation work is extremely troublesome.
In order to solve such a problem, in the case of a cable laying/maintenance construction in which laying and characteristic evaluations of several hundred optical fibers are carried out per day, in order to reduce these works, a cable laying/maintenance construction using an optical fiber measuring method called “sequential measurement” has been carried out in which a series of measurement procedures (measurement conditions, a distance range, a pulse width, a wavelength, and the like), and file naming rules are provided in advance, and measured data of an optical fiber are recorded in a file by automatically executing evaluative measurement by connecting an optical fiber to an OTDR.
However, even by such “sequential measurement”, in fact, there are cases in which the relevance between the file name set in advance and the optical fiber actually measured disappears due to a change in a file name set in advance, skipping of measurement of optical fibers depending on progress, changes in operations of a cable laying/maintenance construction, and the situation of a measuring site or an optical fiber. Therefore, there is the problem that it is impossible to flexibly respond to the situation on-site by procedures of such “sequential measurement”.
Further, in a file recorded by such “sequential measurement”, there is less relevance between a file name set in advance and measured data in which an optical fiber has been actually measured and recorded. Therefore, when an operator brings a file in which measured data of an optical fiber has been recorded back to an office to generate a report, it is sometimes necessary to verify the relevance between the measured data and the file name again, or to change the file name, and therefore, there is a problem that it requires more operation time, which is troublesome in the same way as a usual cable laying/maintenance construction.
Pat. Document 1: Jpn. Pat. Appln. KOKAI Publication No. 4-158237